Question

The number of unpaired electrons in gaseous species of $M{n}^{3+}$, $C{r}^{3+}$ and $V^{3+}$ respectively are_____and the most stable species is_____.

• A. $4$, $3$ and $2$ ; $V^{3+}$
• B. $3$, $3$ and $2$ ; $C{r}^{3+}$
• C. $4$, $3$ and $2$ ; $C{r}^{3+}$
• D. $3$, $3$ and $3$ ; $M{n}^{3+}$

Answer 1

Answer: (C)

$M{n}^{3+}=3d^4=4$ unpaired electrons, $C{r}^{3+}=3d^3=3$ unpaired electrons, $V^{3+}=3d^2=2$ unpaired electrons. $C{r}^{3+}$ is most stable out of these in aqueous solution because it has half-filled tlg level (i.e., $t_{2g}^3$).